Spacecraft-to-launch-vehicle transition

The invention lies in a support transition which is affixed to a spacecraft for supporting the spacecraft on a support ring of a booster or launch vehicle. The transition is in the general form of a ring defining a longitudinal axis parallel to the axis of the spacecraft and the booster. The transition has a circular end adapted to mate with the booster support ring, and a polygonal end adapted to mate with the spacecraft, and makes a smooth transition between ends. The circumference of the transition, at any cross-section transverse to the longitudinal axis, is constant. The transition is advantageously made of a composite material such as fiber-reinforced solidified liquid or carbon-fiber reinforced resin. In a particular embodiment, the polygonal end is a square rectangle, with four straight sides and rounded corners. In a set of spacecraft, the transition remains the same size.